It is known to place a resonator in an engine air intake system for attenuating engine noise. One form of resonator comprises an expansion chamber; another, one or more venturi sections; still another a Helmholtz resonator. Examples are disclosed in the following U.S. patent documents: U.S. Pat. Nos. 4,936,413; 4,790,864; 4,782,912; 5,162,621; and 5,163,387. From certain of these it is known to fabricate the resonator expansion chamber as a single, blow-molded plastic part.
The present invention relates to an engine air intake system having a novel resonator that is suited for fabrication from one or more plastic parts using blow-molding, or injection-molding and vibration welding procedures.
According to a first general aspect, the present invention relates to an internal combustion engine air intake system comprising a resonator for attenuating engine noise that propagates through the system in a direction opposite intake air flow, the resonator having a walled expansion chamber, an inlet pipe for conveying intake air to the expansion chamber and an outlet pipe for conveying air from the expansion chamber, characterized in that the inlet pipe comprises an upstream end via which air enters the resonator, a downstream end via which air passes from the inlet pipe to the expansion chamber, and a venturi section through which air passes before entering the expansion chamber, and the outlet pipe comprises an upstream end via which air passes from the expansion chamber, a downstream end via which air leaves the resonator, and a venturi section through which air passes after leaving the expansion chamber, and characterized further in that the downstream end of the inlet pipe and the upstream end of the outlet pipe are not aligned with each other at the expansion chamber.
Some of the more specific aspects of this first general aspect of the invention relate: to the inlet pipe, the expansion chamber, the outlet pipe, and the venturi sections being integrated into a unitary part made of plastic; and to the inlet pipe being also communicated to the expansion chamber by aperture means to also render the expansion chamber a Helmholtz resonator for frequencies related to a dimensional characteristic of the aperture means.
Another general aspect of the invention relates to: an internal combustion engine air intake system comprising a resonator for attenuating engine noise that propagates through the system in a direction opposite intake air flow, the resonator having a walled expansion chamber and piping comprising an inlet pipe for conveying intake air to the expansion chamber and an outlet pipe for conveying air from the expansion chamber, characterized in that the piping comprises a venturi section through which intake air passes and in that the piping is also communicated to the expansion chamber by aperture means to also render the expansion chamber a Helmholtz resonator for frequencies related to a dimensional characteristic of the aperture means.
One of the more specific aspects falling within this latter general aspect of the invention involves the resonator being a single, blow-molded plastic part, or a part formed by uniting several injection-molded parts.
Further features and characteristics of the invention, along with those already described, will be seen in the ensuing description and claims which are accompanied by drawings. These drawings disclose a presently preferred embodiment of the invention representing the best mode contemplated at this time for carrying out the invention.